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Extension of the historic range of Pristis pristis on the east coast of Australia
Abstract
Populations of all species of sawfish have been depleted worldwide, and sawfish are now absent from much of their historic range. Much of the historic sawfish capture and encounter data does not provide information useful for species identification, and so cannot be used to reconstruct the historic ranges of the different species. For a long time, these data were also not easily accessible, as they were not digitised. Thus historic populations and distribution ranges of the
different species could have been underestimated. Here, we examine historical newspaper articles (n ¼ 237) from the Australian National Library’s online database ‘Trove’, that were found by searching for the generic term ‘sawfish’.
Articles were examined for information that could be relevant to sawfish biology and distribution, as outlined in the IUCN’s Sawfish Conservation Strategy, such as date of capture, circumstance of capture, location, animals’ weight and length, and potential species identifiers. One of the articles is presented in detail as it outlines a capture of Pristis pristis outside of the currently described range of this species, by over 800 km. This evidence highlights the need for a global examination of historical print resources, which use generic terminology to report sawfish encounters. Examination of global news resources may help provide greater understanding of the full historic range of sawfishes, and allow a more accurate estimation of areas in which they no longer occur.
... Measuring the success of conservation and management actions for sawfish is limited by a lack of data on population trends. Conspicuous features of sawfish, such as their large body size and toothed rostra, along with apparent high former abundance in many regions, have enabled historical population de clines and range contractions to be inferred from numerous sources, including fisheries catch data (Thorson 1982, Simpfendorfer 2002, shark control programs (Everett et al. 2015, Wueringer 2017, interviews (Jabado et al. 2017, Braulik et al. 2020, Tanna et al. 2021, museum records (Ferretti et al. 2016), historic newspapers and photographs (Hudgins et al. 2020), and preserved rostra (Leeney & Downing 2016, Fearing et al. 2018. ...
Northwestern Australia is thought to have some of the world’s last remaining viable sawfish populations, although little quantitative data exists on their status or trends. This study examined 17 years of logbook bycatch records (n = 815) for green sawfish Pristis zijsron and narrow sawfish Anoxypristis cuspidata from a trawl fishery operating on the Australian North West Shelf. Incidental sawfish captures by the fishery are rare, occurring approximately once every 75 trawls (~199 trawl hours). To standardize catch rates and account for excess zeros in the data, we employed generalized additive models for location, scale, and shape (GAMLSSs) using a zero-inflated Poisson distribution. For green sawfish, catch rates approximately doubled over the study period, while an oscillating trend was observed for narrow sawfish catch rates. Reported captures occurred throughout the management boundaries of the fishery, which operates in mid-shelf waters from 48 to 121 m. A weak seasonal signal in catch rates was detected for both species, with the highest capture numbers occurring during autumn-winter, consistent with an expected inshore migration for parturition during spring-summer. Logbook trends were partly corroborated by independently verified data collected in a subset of years, which also showed an increasing proportion of green sawfish in the catch. Our findings emphasize the importance of sawfish populations in northwestern Australia within the context of global conservation efforts for this taxon.
... The potential for reconstructing historic distributions has been demonstrated using multiple techniques, including interviews with Aboriginal communities (Burbidge et al. 1988;Ziembicki et al. 2013;Trageser et al. 2017) and other long-term residents (Abbott 2001(Abbott , 2006, natural history collections (DeWalt et al. 2009;Saarinen and Daniels 2012), journals of explorers and early naturalists and travellers (Kerle et al. 1992;Denny 1994;Silcock et al. 2013), and, increasingly, digitised newspaper archives (Cochran and Elliott 2012;Fairfax 2019;Cooke 2020;Hudgins et al. 2020). ...
Context Understanding historical distributions of species informs their ecology and response to threats, which can support management of surviving and translocated populations. Like many critical weight-range mammals in Australia, the greater bilby (Macrotis lagotis) has experienced major declines since European colonisation. The past distribution of bilbies in eastern Australia remains uncertain owing to the rapidity of their decline, their cryptic and nocturnal nature, and the paucity of specimen records. Aims We aimed to systematically collate, geo-reference and attribute bilby records from eastern Australia to better inform their historical distribution, habitat preferences, patterns of decline and response to threats. Methods We searched explorer and early settler journals, the digitised newspaper archive, interviews with long-term residents, Aboriginal language resources and ethnographies, place and property names, unpublished datasets, and documented locations of now-inactive bilby burrows. Records were geo-referenced and attributed with date, record type, source, location precision, bioregion, habitat and local abundance. The former distribution of bilby habitat in Queensland was modelled using Maxent, and the likely former occupancy of bilbies was identified using vegetation mapping. Key results More than 250 bilby records were found, only 34 of which appear in the Atlas of Living Australia. Sixty-five per cent of the records were attributed either ‘certain’ or ‘good’ reliability. Bilbies formerly occurred over most of inland New South Wales and the southern half of Queensland in areas receiving <600 mm average annual rainfall, in a wide variety of habitats. By the 1930s, bilbies were largely restricted to their current core range in south-western Queensland. This contraction in range coincided with the northward spread of rabbits and foxes. Conclusions Bilbies had a more contiguous distribution and occupied a wider range of habitats than was previously recognised. The species persisted in apparently isolated patches to the south-east, west and north of its present distribution until the 1970s, suggesting recent declines around the peripheries of its current range. By the 1990s, bilbies occupied <3% of their pre-1900 range in eastern Australia. Implications This work details changes in bilby distribution and provides key context for interpreting contemporary survey results. It also identifies areas where further surveys are required and may assist in selecting habitat for future translocations.
... pristis, P. zijsron, and A. cuspidata) are known to occur on the east coast of Queensland. Their distributions within the Great Barrier Reef Marine Park are not well understood (Harrison & Dulvy 2014, Department of the Environment 2015, Wueringer 2017, Hudgins et al. 2020. P. pristis is likely still present in waters north of Cairns (Last et al. 2016. ...
Globally, populations of sawfishes (Batoidea: Pristidae) have declined due to directed fishing and bycatch. Before international trade protection, sawfish rostra were often collected as trophies, and sawfish fins could fetch some of the highest prices in the shark fin trade. Australia is now considered a global stronghold for 4 out of 5 species. The present study analyses data of 723 sawfish rostra from all 4 Australian species that were caught in Queensland over the last 100 years. The majority of rostra (92.2%) originated from gillnet captures. Morphometric data from rostra were used to calculate sawfish total lengths and ages at mortality using published ratios. Rostra were split into the mass retention subgroup (n = 569), which originated from ≤5 active commercial inshore gillnet fishers with known large geographic origin regions and decades of origin, and the small-scale retention subgroup (n = 154), for which individual years and locations are known. Across all regions of Queensland, species composition changed significantly before and after the year 2000. After 2000, Anoxypristis cuspidata became the dominant species on the east coast. Large adult Pristis zijsron were present across Queensland before 2000 and numbers declined after this. The commercial gillnet industry likely impacts all life history stages of sawfishes. Since 2002, it has become compulsory for Queensland’s commercial fishers to report interactions with sawfishes in SOCI (Species of Conservation Interest) logbooks. Comparison of rostra from gillnet captures with logbook data indicates that underreporting is higher than previously assumed.
Many elasmobranch populations were already depleted well before fishery surveys had even started, which means historical investigations are needed to reveal their ignored declines. This is probably the case for the Bramble shark Echinorhinus brucus (Bonnaterre, 1788) whose populations in Europe are suspected of having decreased significantly. In order to document this data deficiency, an inventory
of Bramble shark material that had been preserved in natural history collections, was conducted in the period 2014-2022. A total of 128 collections were contacted around the world, and additional sources of information were traced and consulted (e.g. collection labels, museum registers, digital databases, index cards, pictures, manuscripts and publications). This resulted in a list of 234 entries, subsequently assigned to 169 individual Bramble sharks. These exhibits are, or had been deposited in 80 different collections, spread over 22 countries, whereas the other 48 collections yielded no results. At least 40 entries are presumed lost, so that fewer than 200 entries have been preserved to date, some of them in bad condition. Due to their historic and scientific importance, extensive efforts to preserve
these specimens are more than justified. A significant number of 64 individuals, representing more than 37% of all specimens that were recorded in this survey, have never been published, and are reported here for the first time. Associated geographical data and collection dates are present for nearly all specimens. These ‘new historical records’ can add significantly to our knowledge of the Bramble sharks’ relative abundance and geographical distribution in time. These data will be included in the ongoing Bramble shark Cold Case, a project that will document its suspected decline, and to implement appropriate conservation measures for this iconic, little-known and endangered shark species.
The rapid expansion of human activities threatens ocean-wide biodiversity. Numerous marine animal populations have declined, yet it remains unclear whether these trends are symptomatic of a chronic accumulation of global marine extinction risk. We present the first systematic analysis of threat for a globally distributed lineage of 1,041 chondrichthyan fishes-sharks, rays, and chimaeras. We estimate that one-quarter are threatened according to IUCN Red List criteria due to overfishing (targeted and incidental). Large-bodied, shallow-water species are at greatest risk and five out of the seven most threatened families are rays. Overall chondrichthyan extinction risk is substantially higher than for most other vertebrates, and only one-third of species are considered safe. Population depletion has occurred throughout the world's ice-free waters, but is particularly prevalent in the Indo-Pacific Biodiversity Triangle and Mediterranean Sea. Improved management of fisheries and trade is urgently needed to avoid extinctions and promote population recovery.
Within the Great Barrier Reef World Heritage Area in Queensland, Australia, lack of information on the distribution of sawfishes presents difficulty for informed management of their habitats and populations. This study aims to provide insights into the historical and current distributions through analysis of sawfish by-catch records from the Queensland Shark Control Program (QSCP), which has protected bathers since 1963 by targeting large sharks. Sawfishes have been caught in 8 of the 10 areas where the QSCP has been active. A total of 1450 captures of sawfishes (all 4 species known from Australia) were reported from 1963 to August 2016, with most ( > 99%) in the 4 most northern areas; Cairns, Townsville, Mackay, and Rockhampton. Sawfishes were mainly captured in gillnets. Most (95.4%) animals were alive when the gear was checked. In Townsville and Rockhampton, standardised sawfish captures have declined over the years. No sawfish captures in QSCP gear have been recorded in 3 areas (Cairns, Townsville, Rockhampton) since gillnets were banned there, but in Mackay, where gillnets are still used, only 4 animals have been caught since 1999. It is recommended that QSCP contractors take more detailed data of future sawfish captures, and that contractors and fishers receive training on releasing sawfishes swiftly and with minimal damage. Moreover, as the use of gillnets in the QSCP has been decreasing over the years, fisheries-independent studies of current sawfish distributions are required.
Sawfishes are the most endangered cartilaginous fishes on the planet. Their external morphology facilitates entanglement in fishing nets and their K-selected life history hinders the recovery of exploited populations. The Eastern Amazon coast (EAC) is known to be an area where sawfishes occur in Brazil, but few studies have been conducted in the area to better understand their biology and ecology. The present study reports sawfish captures along the coast of Brazil’s second largest state. Data were collected from interviews with fishermen, a literature review, and media reports. In total, 23 captures were recorded between 1984 and 2016. Records include adults, a pregnant female with near-term embryos, juveniles, and young-of-the-year specimens. Most catches were reported in the Canal do Navio, an area under strong human pressure. Sawfish saws are valuable items and, for many anglers in precarious economic and social situations, high market prices eclipse the fishing prohibitions laid down under federal laws. Urgent research is required to understand sawfishes’ life history, identify their critical habitats, and effectively manage and conserve these species along the EAC.
Sawfish are arguably the world's most imperilled marine fishes. All five species are classified as highly threatened with extinction: three are Critically Endangered (smalltooth sawfish Pristis pectinata , largetooth sawfish Pristis pristis, and green sawfish Pristis zijsron ); two are Endangered (narrow sawfish Anoxypristis cuspidata , and dwarf sawfish Pristis clavata ).
Sawfishes are threatened primarily due to a combination of their low intrinsic rates of population increase, high catchability in fisheries, and high value. Sawfishes are among the world's largest marine fishes, and they are caught by a wide range of fishing gears owing to their tooth‐studded rostra being easily entangled. Sawfish fins are some of the most valuable for shark fin soup, and their rostra have long been traded as curios. In addition, they inhabit shallow coastal waters, estuaries, and rivers of the tropics and subtropics, down to a maximum depth rarely exceeding 100 m and are associated with threatened mangrove and seagrass habitats.
Historically, sawfishes were distributed in the coastal waters of 90 countries and territories. Over the past century, their geographic distribution has been greatly diminished. For example, the smalltooth sawfish is now found in <20% of its former range. Globally, sawfishes are now entirely absent from 20 countries; 43 countries have lost at least one species.
Sawfishes are legally protected, to some degree, in 16 of the 90 range states. These safeguards encompass, on average, 81% of their Extant distribution; however, the quality and breadth of protection varies dramatically across countries and species. Smalltooth sawfish currently has the least amount of such coverage of only half (49%) of Extant distribution.
The global conservation strategy specifies actions to protect sawfish and their habitats. Such actions are urgently warranted to avoid global extinction and to restore robust populations for the benefit of coastal ecosystem function and biodiversity.
© 2014 The Authors. Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons, Ltd.
Intergenerational loss of information about the abundance of exploited species can lead to shifting baselines, which have direct consequences for how species and ecosystems are managed. Historical data provide a means of regaining that information, but they still are not commonly applied in marine conservation and management. Omission of relevant historical information typically results in assessments of conservation status that are more optimistic, recovery targets that are lower, and fisheries quotas that are higher than if long-term data were considered. Here, we review data and methods that can be used to estimate historical baselines for marine species including bony fishes, sharks, turtles, and mammals, demonstrate how baselines used in management change when historical data are included, and provide specific examples of how data from the past can be applied in management and conservation including extinction risk assessment, recovery target setting, and management of data-poor fisheries. Incorporating historical data into conservation and management frameworks presents challenges, but the alternative—losing information on past population sizes and ecological variability—represents a greater risk to effective management of marine species and ecosystems.
Effective management of critically endangered sawfishes can be a difficult task, in part due to interspecies misidentification. Current methods for identifying sawfishes can be impractical as they are based on morphological features that are often unobservable. Further exploration is required to develop a more reliable means of identification.
This study explored the utility of sawfish rostra in determining the species, size and sex of sawfishes, as rostra are commonly the only feature of a sawfish observed by fishers or present in public and private collections.
A morphometric and meristic database consisting of over 1100 narrow sawfish ( Anoxypristis cuspidata ), dwarf sawfish ( Pristis clavata ), largetooth (or freshwater) sawfish ( Pristis pristis ; formerly Pristis microdon ) and green sawfish ( Pristis zijsron ) rostra from Australian waters, was statistically analysed.
Identification of sawfishes was found to be possible through the use of the variables: inter‐tooth spacing, standard rostrum width/standard rostrum length, standard rostrum length/total rostrum length, rostrum tip width/standard rostrum length, and/or rostral tooth count range, although the distinguishing variables were species‐dependent.
The relationship between standard rostrum length and total length was also observed to vary substantially between most species. Models for estimating total length from standard rostrum length are provided.
This study has provided a tool that can be used to identify accurately the species and size of sawfishes by their rostra, and therefore can assist in clarifying historical and contemporary sawfish records, nomenclature and distributions. A better understanding of these issues should allow sawfish conservation strategies to become more focused, and thus more effective.
Copyright © 2013 John Wiley & Sons, Ltd.
Pristis microdon, P. zijsron, P. clavata and Anoxypristis cuspidata are distributed throughout the Queensland section of the Gulf of Carpentaria, Australia. In a survey of the four species, Anoxypristis cuspidata was the most abundant and was recorded in both the inshore and offshore set net fisheries. The size distribution and catch locations of A. cuspidata suggest that the inshore area to a depth of 10m may be the preferred habitat for juveniles of this species, while adults primarily occur offshore. Pristis microdon, P. zijsron and P. clavata were recorded only in the inshore fishery with catches dominated by immature animals. Pristis microdon was caught in the inshore fishery late in the monsoonal wet season (February to April) and inhabited both freshwater and estuarine environments. Pristis zijsron occurred only on the sand and mud flats outside river mouths whilst P. clavata inhabited both the sand and mud flats and upstream estuarine habitats. Observations on reproductive staging and the capture of neonate specimens suggest that in all four pristids, pupping occurred through the wet season until the beginning of the dry season in May. A seasonal set net closure for the barramundi, Lates calcarifer and shark fisheries, which has been in place since 1980 in Queensland Gulf waters, therefore offers a measure of protection to breeding female sawfish and their offspring.
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Telegraph 11 October 1926, p. 1.
- Dulvy